Ravelproof seam and method of making the same



Nov. 15 i949 F. F. zEn-:R

RAVEL-PROOF SEAM ND METHOD OF MAKING THE SAME Filed June 8, 1948 NORMA LRELATVELY L/GHT TENS/0N I L nLx/TQ/EE/vson /T NVENTR. W/federz'c F Ze BYATTORNEY WITNESS Patented Nov. 15, 1949 -:v

RAVEILPR'OOFSEAM ANUMETKHTF Y MAKING THESAME Frederick F.. Zeier,I

The Singer,Manufacturing.l Gompan;

Strateldyonm; assignoretof Elizabeth,.

N. I., a corporation of"New Jersey A Application J une 8,1948;*-S`er'ial-No.` SLGG'S?` ieolains. (o1. ii-zfasal.

Thissinvention relatestc a ravelfproofseami and-.ae method of; making.`the.- same.-

lnfcenta-in articles ofiwearing apparel, such, for example;Aasfovera-lls, dungar-ees and. similar artiolesofi work.. clothing;which:r are given hardv usage.: andesubjected toe thex action of: briersand theflilre;A itfisnot uncommon for the threads of'V thee sewed;seams.v toV loewor-n through or-` broken. These seams: areausually: offAthe chain-stitch: variety1 andlwhen a-Hthreadi is ruptured the seam willreadily ravele y This inventionshassaszan obect to provide asewedfseamfwhich; when-onev or more threads: thereof areibroken; wilkbe locked`against ravelling?.

Anotherobj ect= offF the invention is toV provide. animproved;method ofmaking.V a ravel-proof sewediseami.- n

These-:objects/have been attained by=makingfa1 conventional.4 sewed seamot a needle threadf and a` primary looper.I threadand? simultaneouslyytherewith incorporating in the seam arnaddi-k tionaliorauxiliaryvthreadfand sotensioning the auxiliary. threadythatit.E willproduce -Y sufficientl friction. on the -loopsf of the other thread;A orthreads, tolaind= theeloopsntogetherandfprevent;` the; threadsf from.lravelling, should! oneor more. ofY the threadsbebrokenr. e

Preferably,but not necessarily; thef auxiliaryI locking; thread. is)relativ-,elylr elastic` (as compared withi the.=otherthreads which" arerelatively in1 elastic)y andf,is-.placedf.in =the seam undera tenssionsuicienttocause the. auxiliary threadi to` v contr-act,, ifbroken,...hut ,not-` sufficient toA causey puckering or shirring of theworkpiece. v

The: terms v elastio1 thread? and:A inelastic thread arer-usedi inithis:` specificationina. relative.- sense, the former.loeing;V intended.toindi-Y catef a. thread adaptedrrto he` stretched substanftiallyiyasforexample, a` nylon or arubber thread;g Whereas the terminelastic thread is intended: tomeana conventional thread of. cotton orthe like.Y l

kBrasil-ingsdepicting my improved seam and; ill'ustratineaa` methodl01E-making. it formI -av part off this disclosure and .in such' drawingsFig. l is a perspective view of. a chain-stitch, seam.4 embodying.` my..inyention with the: seam mad'efin .theiair ora-part from a.workpiece:v

Eig.M 2.-i's. an under yside.view ofi.A a portionof: a1- workpieceA and,my improved ravelergroof`v seam; therein the. threads; of. thefrseam;vbeing: shownf. substantially. ini therpositions which? they. occupyl inVan,,unbrokenseam...l

Eig... 3751's. afyvview. similantcbFigf. muti-illustrate. faslwilhbeseemfrormaninspectwnof ing thefsnarling@actionyrof thethreadsiwhicir.takes; placeautomatically; when thef threads.Y of the? seamare broken'.

Fig. 4 is a diagrammatic viewf-ofacertainstitchfV forming;inst-rumentalitiesp-whi'ch may' befused tot make myY improved-f seamfandgalso illustrating: diagramm'atically theY application; of; unequaltensions toA the two. looperfthreadsaz Referring morel snecicallyy to;the); drawings;

-, the.- improved seam issh`ownias1A comprising; an;

upper cir-'needle .thread Ii which isffpassedithrough; the? werkeY W atspaced: intervals, and' formed: into; loon le at-theunder.r side-,ofi`the w,ork. Rassing; through; and surroundingthe; loops le are-louper ofa' main: interlockinggor: looper thread; 2.

A-s shownfin-;Eie-'.:4; ,thefthreadse ll' and- .2 arecar.- ried;zrespectively, by; afk needlerNland: a;V looperiljl, These threads arerelatively inelasticf andi` are;A concatenatedf in the; manner off;azconventional r.xvo+th-i'.eadchain-stitchyseamz; Inf-their travel; fromtheir respective sources'v of.; supply.t to the..

needle N and: thee loopenKV 13,..respectivelmA the@ threads I- and2 2-passqthroughsuitable tension; devices represented.- diagrammatically;in: Fig.' 4;',

as-t and; te respectively.

Cooperating with the threadsnl and;2;.andrcorrv catenatedz with :theformer; is; a; th-indor t,auxiliaryv locking threads which-r alsof is;carriech by; the; looperell.-` andA whichf traverses thef same course-.f

asthethread-Zathroughoutthefseam length'` The@ thready 3- isA preferablymade. of. nylon. rubber lor." other material'v which isr more elasticthan the; material (e. g, co1:onf) -Y of? whichi the: threads; and 2 aremade; -Inits:travellltoitheflooper the: thread 3; also/passesffthroug-hi tensioning means shown diagrammatically in@ Eig'. 41;and."

designated generally,V as; 'llhis tensioning meansA appliesftothe'thread: Ssassomewhatigreater; tensionethan: the tension-pwhichA isapplied tos the. thread Zrso thatv the thread; 3,1 asfincorporatedt inl'the" seam; exerts: a binding action. onA the: threads,` If and-'2.1 Whenther threanri is made. of; rela,- tively: elasticir material; this;ad'diti-onahv tensionicauses f the tlneadz to be` incorporatedf in'thefseam in a stretched condition. The.ten'd'errcyf-ofthel thread.'l Sito;contract,` however;l isV not sufliciently greatgto cause,- pfucliering:of'f'thawork; especiallyYAY whenvsewing: througlir relatively heavymaterialk such, as. is used fonmakingr overalls'. and:l other workclothes;J Wshile. the threadid follows the.:

same; generali course: asi .thethread: 2`: throughout. the:seam;-neyerthelessg. duertotwist.: and unequal?A tension; insthe threads,theloeps ofth'e thread frequently; crossioverf tirez-loops .ot-'thethread meer. frm-sy causes a binding of the threads and helps to preventravelling of the seam' when the threads are broken, as hereinafter willbe described.

The locking thread 3 is preferably materially smaller in cross-sectionalarea than the looper thread 2. This prevents the seam from being undulybulky at the under side of the work and yet does not interfere with itsfunction of locking the threads together.

Inasmuch as the tensioned elastic thread 3 frictionally engages both theneedle thread I and the looper thread 2, if either or both of thosethreads should be broken the gripping action of the auxiliary thread 3will cause the threads l and 2 to be bound together frictionally andthus prevent ravelling of the seam.

Should the elastic thread 3 be broken, either alone or with the threadsI and/or 2, contraction of the thread 3 will cause it to snap back andshift the threads comprising the last several stitches of the seam intoa malformation, as illustrated atv m in Fig. 3, thereby snarling ortangling the threads, which additionally prevents the seam from beingravelled.

In making this improved ravel-proof seam the needle and looper arethreaded with the threads l and 2, respectively, as is customary intwothread chain-stitch sewing machines, the threads passing throughsuitable tensioning means. In addition, the auxiliary thread 3 is passedthrough a heavier tension than is the looper thread 2, and also isthreaded through the looper, which may have a somewhat enlarged threadgroove and thread eyes to accommodate the two threads.

The machine is then operated in the manner common to two-threadchain-stitch sewing machines and produces the above described ravelproofseam.`

It isY recognized that it is not broadly new to sew a seam with a singleneedle thread and two similar looper threads but, insofar as I am aware,no one heretofore has sewed such a seam in which (a) both looper threadsare carried by the same looper and follow the same course throughout theseam length and have materially diierent crosssectional areas; (b) inwhich one of the looper threads is under greater tension than the otherthereby causing the greater tensioned thread to produce a binding electon the other threads of the seam; or (c) in which that one oi the looperthreads which is subjected to the greater tension also has greaterelasticity than the other and tends to contract andV snarl the otherthreads when the elastic thread is broken.

Having thus set forth the nature of the invention, what I claim hereinis:

1. A ravel-proof seam comprising an upper thread formed with a pluralityof loops projecting through a workpiece at spaced intervals, a lowerthread concatenated with the loops of said upper thread at the underside of the workpiece, and a locking thread concatenated with the loopsof' said Yupper thread coincident with said lower thread and tensionedto exert a binding action on the other threads.

2. A ravel-proof seam comprising a first thread located at one side of aworkpiece and having loops projecting therethrough at spaced intervals,a second thread at the opposite side of the workpiece and having loopsconcatenated with the loops of said first thread, and a third thread atsaid opposite side of the workpiece and concatenated with the loops ofsaid iirst thread similarly to and coincident with said second thread,said third thread being more heavily 'tensioned than said second threadand exerting a binding action on the loops of the other threads.

3. A ravel-proof seam comprising a needle thread extending along oneface of a workpiece and having a plurality of loops projectingtherethrough at spaced intervals, an inelastic looper thread extendingalong the opposite face of the workpiece and concatenated with the loopsof said needle thread, and an elastic looper thread traversing the samecourse as said inelastic thread and concatenated with the loops of saidneedle thread, said elastic thread normally being tensioned andstretched in said seam and adapted to contract and snarl the otherthreads when the elastic thread is broken, thereby to prevent ravellingof the seam.

4. A ravel-proof seam comprising an upper thread formed with a pluralityof loops projecting through a workpiece at spaced intervals, a lowerthread concatenated with the loops of said upper thread at the underside of the workpiece in a manner common to two-thread chain-stitchseams, and a seam-locking thread concatenated with the loops of saidupper thread coincident with said lower thread and tensioned'to exert abinding action on the other threads, said seamlocking thread beingmaterially smaller in crosssection than said lower thread and beingtwisted thereabout throughout the seam length.

5. A ravel-proof seam comprising a needle thread extending along oneface of a workpiece and having a plurality of loops projectingtherethrough at spaced intervals, an inelastic looper thread extendingalong the opposite face of the workpiece and concatenated with the loopsof said needle thread, and an elastic locking thread traversing the samecourse as said looper thread and concatenated with the loops of saidneedle thread, said elastic locking thread being materially smaller incross-section than said looper thread and being embodied in said seam ina stretched condition.

6. A ravel-proof seam comprising a rst thread disposed on one face of aworkpiece having loops projecting through said workpiece at spacedintervals, a second thread at the opposite side of the workpiece andhaving loops concatenated with the loops of said first thread, and athird thread at said opposite side of the workpiece and concatenatedwith the loops of said rst thread, one of said three threads beingrelatively elastic and normally being tensioned and stretched in saidseam and adapted to contract and snarl the other threads when one ofsaid threads is broken.

7. A ravel-proof seam formed in a workpiece and comprising, a rst threadformed at intervals into work-penetrating loops, and unequally tensionedsecond and third threads concatenated with and anchoring the loops ofsaid rst thread in the work.

8. A ravel-proof seam formed in a workpiece and comprising, a firstthread formed at intervals into work-penetrating loops, and unequallytensioned second and third threads of different elasticity concatenatedwith and anchoring the loops of said first thread in the work.

9. The method of making a ravel-proof seam which comprises successivelyprojecting loops of a thread through a workpiece, concatenating withsaid loops other loops formed in main and aux-I iliary interlockingthreads havingsubstantially iary thread to bind together the loops ofthe other threads to prevent :ravelling of the seam upon breakage of anyone of said threads.

10. The method of making a ravel-proof seam which comprises successivelyprojecting loops of a needle thread through a workpiece at spacedintervals, concatenating with said loops other loops formed in main andauxiliary looper threads, and subjecting said looper threads to unequaltensions whereby the loops of the greater tensioned looper thread exerta gripping action on the needle thread and the other looper thread.

11. The method of making a ravel-proof seam which comprises successivelyprojecting loops of a needle thread through a workpiece at spacedintervals, concatenating with said loops other loops formed in main andauxiliary looper threads, said auxiliary looper thread being relativelyelastic, and applying a tension to said auxiliary looper thread to causeit to be embodied in the seam in a stretched condition.

12. The method of making a ravel-proof seam which comprises extending arelatively inelastic thread along the upper face of a workpiece,projecting loops of said thread through a workpiece at spaced intervals,concatenating with said loops at the under side of the workpiece aretaining thread and a locking thread, said retaining and lockingthreads following substantially the same course throughout the seam butcrossing each other at various places along the seam, and applying tosaid locking thread suicent tension to cause it to bind the loops of theretaining thread against ravelling.

13. The method of making a ravel-proof seam which comprises successivelyprojecting loops of a needle thread through a workpiece at spacedintervals, ccncatenating with said loops other loops formed in main andauxiliary looper threads, one of said threads being relatively elastic,and applying a tension to said relatively elastic thread to cause it tobe embodied in the seam in a stretched condition.

FREDERICK F. ZEIER..

No references cited.

